@sawguy

What type of idlying issues did you have that were solved by the new ecu.

I've had idlying issue for going on 2 years now. Changed quite a few things. The mechanic even speculated it could be the ECU. My trucks runs great 99.99% of time but at idle I get some random misfire codes. No flashing or power loss, just a code and then it is gone.

what's the IDLE rpm? too low and it can cause issues.

My rpm is normal 700-ish.

My idle cold was 1800 ish. Wouldn't come down until engine was fully warmed up and then it was still 8 to 900. Threw a P0505 code so I started with the MAF sensor then the IAC and finally the ECU. I took the old one apart and found a fried resistor.

It could be the neutral safety switch, or at least check the wiring to it if you were able to crank it in N for some time.

Fuel, compression, spark. One or more is missing.

Concerning the ECU I have seen 2 Honda Civic ECUs that have had fried resistors in the last four months.

This whole neutral safety switch thing really confuses me.

If its job is to let you *start* while in P or N ONLY... when it is *broken* wouldn't you think you *can't* start in P or N?

You and others are saying it could be bad because you can start in N... isn't that it's job?

Or is it that OP *can't* start in P, but can in N, so it is serving 50% of its function and thus could have some bad wiring? Or when bad, it can go haywire and just kill the starter no matter what gear?

The ones I have dealt with (not for the 4runner) the linkage over the years causes wear on the gears and springs, thus the switch thinks it isn't in P when it is, can be started in D, etc. If the linkage is bent in any way the wear can be accelerated. Also dirt as well as snow can get into the electrical connection with time.

Some can be adjusted (mostly older ones, even on the Aisin AW4) but I don't think ones for the A340s can be.

Dont dogg ur mechanics. Ur entightled to a second opinion. If hes an old timer he most likely knows what he is doing and all the usual suspects are not causing ur problem. That is usually the most frustrating and there is often no real tests for a bad ecu. All you can do it check everything in the system and if everything checks out there is really no other options but to try a computer. No matter how good you are there are always head ache cars like this every once in a while. Its difficult to do anything with only a 1 hr time allotment. They should indeed call you back and update you with what they have come up with and ask for more time. Its up to the customer to procede further or not. Chances are the mechanic has spent 2-3 hours troubleshooting. You should still be willing to pay for your original diag/check out fees. Not all problems can be pinned down in just 1hr. We do live in the real world.

Ecus can go bad. Corroded or leaking capacitors. I have seen intermittant poor running fuel smelling exhaust on early lexus cars. Nothing you can do to test for it. Just have to take whatevr clues you can get and use experience and trust your gut. Maybe try opening ur ecu and look for leaking capacitors they will often times be obvious. If nothing obvious maybe look else where. Bad relays will cause you to lose fuel pressure or spark. Is there anything aftermarket that has been added or changed to the vehicle. More times than not the owners have had other repairs made or changed parts themselves and that is where the problems lie. A lot of diyers cause more problems than they fix.

Need Help! I have a strange situation. My car over-heated without warning but that's not the problem. I repaired the engine and now my car won't start due to something is wrong with the electrical or ecm. No spark or fuel pressure also. First thing that's strange, it's trying to start in the "on" position, not start and keeps cranking until I remove the neg cable or put the car in drive, other than neutral or park. I replaced the ignition switch, starter, neutral safety switch, numerous relays and even tried and wasted my money on a clone ECM with the same symptoms. This driving us crazy trying to find the problem. Anyone have any ideas as to what's happening to my car? Can a dealer check the ECM if it's any good? Ant thoughts?

When youbsaybyou fixed it after overheating, what did you do?
Second, did you check or change out the EFI relay?

I’m having the same issue ecu is not communiting... I checked tthe hot side of the efi relay got 12.34 volts key off... as well as at the fuse... checked for continuity as well no problem... next is to check the red and white wires at the ecu that provide the ecu power as well as the violet wire but need to figure out which one here’s a link as to what I’m following...
I’m thinking it is a wiring issue; only because of the fact that is your ecu goes out it won’t be intermittent. once in a while I can start my runner back up and even with a known good ecu I have the same issue... so the issue was verified...
so here is the link please read through the whole feed:
3VZE not sparking & Check Engine light won't come on. - YotaTech Forums